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Submitted on: 04 July 2005.
Revised on: 03 October 2005.
Accepted on: 25 October 2005.
___________________Communications in Applied and Industrial Mathematics
Submitted on: 25 February 2011.
Revised on: 14 May 2011.
Accepted on: 01 July 2011.
___________________Communications in Applied and Industrial Mathematics
Submitted on: 03 September 1999.
Revised on: 14 December 1999.
Accepted on: 29 January 2000.
___________________Communications in Applied and Industrial Mathematics
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